This talk is about our experience in the dialogue between industry and
theory, in the context of W3C's working group on a description language
for web services, called Choreography Description Language (CDL). We
shall discuss how such a dialogue can not only benefit industry but also
can stimulate a theoretical research.

Participation in W3C's standardisationon process started three years
ago, when the chair of W3C's web service WGs invited three pi-calculus
experts, Robin Milner, Nobuko Yoshida and me, to the CDL WG. CDL is
intended as a description language for web services, and both for
general and specific features, the pi-calculus foundation can be very
useful.

Our participation in WG resulted in a standard which will become a W3C
recommendation soon. It has also led to a new principle of programming
which consists of two distinct ways for describing communication-centric
software, one centring on global message flows and another centring on
end-point behaviour, distilled as formal calculi. The two paradigms of
description share a common feature, structured representation of
communications. The global calculus originates from CDL itself, while the
local calculus is based on the pi-calculus, one of the representative calculi
for communicating processes.

The theoretical part of the talk will illustrate these two frameworks using
simple but non-trivial examples, present the static and dynamic semantics
of the calculi, and show a basic theory of end-point projection --- that any
well-formed description in the global calculus has a precise representation
in the local calculus.

The talk will discuss potential forms of collaboration between industry
and theory, what merits such collaboration may have for industry, and
how this can give positive feedbacks to academic research.